Honeycomb extrusion molding mouth ring

ABSTRACT

A die for extrusion molding of a honeycomb which comprises a structure provided with a groovy slit ( 2 ) formed by cell blocks ( 3 ) on a front face thereof, and additionally provided with a puddle inlet, on a back face thereof, communicatively connected with the slit ( 2 ), wherein each cell block ( 3 ) has a soft film ( 16 ) on a hard film ( 14 ) formed on outermost surfaces of the slit ( 2 ) and puddle inlet fabricated in a cell-block body ( 10 ). According to the die for extrusion molding of a honeycomb, a dimensional error of the die is possible to be eliminated, a stable force of extrusion friction is possible to be maintained, both extrusion moldability and abrasion resistance are possible to be excellent, and additionally an adjustment of the die at the time of extrusion molding can be performed easily.

TECHNICAL FIELD

[0001] The present invention relates to a die for extrusion molding of ahoneycomb.

BACKGROUND ART

[0002] Heretofore, as a die used in extrusion molding of honeycomb,there has been known the die for extrusion molding of honeycomb,provided with groovy slits on the front face thereof which are formed bycell blocks, and provided with puddle inlets on the back face thereofwhich are communicatively connected with the slits.

[0003] In such a die for extrusion molding of honeycomb, for the purposeof adjusting the slit widths between the respective cell blocks andenhancing the durability of the dies, for example, a surface treatmentis performed along the line of forming a nickel plating layer (a firstcoating film) of 10 to 70 μm on the surface of a cell-block body, andthen forming, on the surface of the nickel plating layer, either acomposite plating layer in which hard powders of SiC, diamond, CBN, orthe like is dispersed in the nickel plating layer or a tungsten carbidelayer of 5 to 15 μm (a second coating film).

[0004] However, in the case where a tungsten carbide film is formed inthe above described surface treatment, it is difficult to adjust thefilm thickness as compared with the plating, and accordingly there hasbeen a problem that dimensional error is caused for the dies in whichthe target dimension±2 μm is required for the coating film (a firstcoating film+a second coating film).

[0005] The above described tungsten carbide film is easily liable tovary in a ratio of W and C, and a frictional resistance with puddlebeing extruded varies due to a variation of the ratio; accordingly, whena difference in a frictional resistance distribution in the formed filmis large, the molding comes to be unstable, and the shapes of the moldedbodies are hardly made stable, and hence the rate of good qualityproducts has remained low.

[0006] Additionally, when the composite plating film is formed in theabove described surface treatment, the hard grains are protruded on thecomposite plate film, and the coefficient of the friction with puddlebeing extruded varies depending on the hard grain density; thus, whenthe hard grain density distribution difference is large, there hasoccurred a fact that the molding comes to be unstable, and the shapes ofthe molded bodies are hardly made stable, and hence the rate of goodquality products is lowered.

[0007] Furthermore, as for the above described die for extrusion moldingof a honeycomb, puddle is made to flow partially, in order to adjust thedimensional dispersion of the die before the extrusion molding of ahoneycomb.

[0008] However, in the case where a tungsten carbide film, a titaniumbased film, or a composite plating film is used for the second coatingfilm, there has been a problem that the adjustment of the die isdifficult and accordingly takes a long time because these films arehard.

[0009] The present invention is achieved in view of the above describedproblems heretofore, and takes as its object the provision of a die forextrusion molding of a honeycomb which is possible to eliminate thedimensional error of the die, maintain a stable frictional force ofextrusion, be excellent both in extrusion moldability and in abrasionresistance, and additionally make the adjustment of the die easy at thetime of extrusion molding.

DISCLOSURE OF THE INVENTION

[0010] According to the present invention, there is provided A die forextrusion molding of a honeycomb, comprising a structure provided with agroovy slit formed on a front face thereof by cell blocks andadditionally with a puddle inlet, on a back face thereof,communicatively connected with the slit, characterized in that each cellblock has a soft film on a hard film formed on outermost surfaces ofboth the slit and the puddle inlet fabricated in the cell block body.

[0011] In this connection, it is preferable that the above describedsoft film has a Vickers hardness of from 500 to 1500, and the thicknessthereof is in a range of from 2 to 10 μM.

[0012] Furthermore, it is preferable that the above described soft filmis an electroless nickel plating film.

[0013] In the next place, in the present invention, it is preferablethat the hard film is a film comprising, as a component, one or morethan one materials selected from a group consisting of W, WC, W₂C, andW₃C, or a CVD or a PVD film comprising, as a component, one or more thanone materials selected from a group consisting of TiC, TiN, and TiCN.

[0014] Additionally, in the present invention, it is preferable that thehard film is a composite plating film having a hard powder of SiC,diamond, CBN, or the like dispersed in a nickel plating film.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 is a schematic front view showing an example of a die forextrusion molding of a honeycomb.

[0016]FIG. 2 is an enlarged front view of a portion A in FIG. 1.

[0017]FIG. 3 is an enlarged sectional view of the portion A in FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

[0018] As described above, a die of the present invention is a die forextrusion molding of a honeycomb which comprises a structure providedwith a groovy slit on the front face thereof formed by cell blocks, andsimultaneously provided with a puddle inlet, on a back face thereof,communicatively connected with the slits, wherein each cell block has asoft film (for example, an electroless nickel plating film) on a hardfilm formed on the outermost surfaces of the slit and puddle inletfabricated in the cell-block body.

[0019] Thereby, the die of the present invention is possible toeliminate the dimensional error of the die, maintain a stable frictionalforce of extrusion, be excellent both in extrusion moldability and inabrasion resistance, and additionally make the adjustment of the dieeasy at the time of extrusion molding.

[0020] Detailed description will be made below on embodiments of thepresent invention on the basis of the drawings.

[0021] FIGS. 1 to 3 show an example of a die for extrusion molding of ahoneycomb; FIG. 1 is a schematic front view, FIG. 2 is an enlarged frontview of a portion A in FIG. 1, and FIG. 3 is an enlarged sectional viewof the portion A in FIG. 1.

[0022] For example, as shown in FIGS. 1 to 3, a die of the presentinvention is a die 1 for extrusion molding of a honeycomb which has astructure provided with a groovy slit 2 on a front face thereof, formedby cell blocks 3, and simultaneously provided with a puddle inlet 4, ona back face thereof, communicatively connected with the slit 2.

[0023] Each cell block 3 comprises a first coating film 12 formed on thesurfaces of the slit 2 and a puddle inlet 4 provided in a cell blockbody 10, a second coating film 14, a hard film, which is formed on thesurface of the first coating film 12 and protecting the first coatingfilm 12, and a third coating film 16, a soft film, which is formed onthe surface of the second coating film 14.

[0024] Here, the die of the present invention is mainly characterized inthat the third coating film 16, a soft film, is formed on the surface ofthe second coating film 14, a hard film, protecting the first coatingfilm 12.

[0025] Thereby, the die of the present invention is possible toeliminate the dimensional error, by forming the third coating film 16 of10 μm or less, either even in the case where the film thickness accuracyof the second coating film 14 is low or even in the case where the dieis required to have the dimensional accuracy of ±2 μm.

[0026] This is because a plating film is relatively easy in controllingthe film formation and film thickness, as compared with a CVD film and aPVD film.

[0027] Additionally, the die of the present invention is excellent inextrusion moldability and in abrasion resistance, because it canmaintain a stable frictional force of extrusion even in the case wherethe condition of the second coating film 14 tends to vary, owing to theformation of the third coating film 16 on the throttle portion 6 (seeFIG. 3), a portion most liable to be worn in the die.

[0028] Incidentally, the above mentioned throttle portion 6 remainsprotected by the second coating film even in the case where the thirdcoating film has been worn; additionally, the extrusion moldability islargely affected by the endmost outlet portion 2, but these portions arescarcely liable to be worn and accordingly the third coating film isscarcely worn, and hence the moldability can be maintained to besatisfactory.

[0029] Furthermore, the die of the present invention gives an easyshort-time adjustment of a slit width W between each of the cell blocks10, by forming the third coating film 16, a soft film, on the surface ofthe second coating film 14, a hard film.

[0030] In this connection, a thickness a of all the coating films (thefirst through third coating films) used in the present invention is notparticularly limited, but it is preferably that it ranges from 20 to 120μm in consideration of the machining difficulty level of the base metal.

[0031] In this connection, the first coating film used in the presentinvention is the substrate to adjust the slit width W between each ofthe cell blocks, and needs not necessarily to be formed, depending onthe hard film formed on the outermost surface; however, in the casewhere the first coating film is formed, it is preferable that it is anelectroless nickel plating film, to the extent of maintaining anappropriate hardness, being relatively easy in film forming, and alsobeing relatively easy in controlling the film thickness.

[0032] Incidentally, it is usually preferable that a thickness b of thefirst coating film is in a range of from 0 to 100 μM.

[0033] Additionally, the second coating film used in the presentinvention is a hard film protecting the first coating film that is abase film; as the second coating film, any of the following films can beappropriately selected to be used: (1) a CVD film composed of one ormore than one materials selected from the group consisting of W, WC,W₂C, and W₃C; (2) either a CVD film or a PVD film composed of one ormore than one materials selected from the group consisting of TiC, TiN,and TiCN; (3) a composite plating film in which the hard powder of SiC,diamond, CBN, or the like is dispersed in a nickel plating film.

[0034] Incidentally, it is usually preferable that a thickness c of thesecond coating film is in a range of from 1 to 70 μm.

[0035] Furthermore, the third coating film used in the present inventionis not particularly limited as far as it is formed of a material withthe Vickers hardness thereof of the order of from 500 to 1500, for thepurpose of making it efficient to correct the dimensional dispersion ofthe die before the extrusion molding of a honeycomb; however, it ispreferable that the third coating film is an electroless nickel platingfilm.

[0036] Incidentally, it is preferable that a thickness d of the thirdcoating film is in a range of from 2 to 10 μm, for the purpose ofdisplaying the effect of the present invention.

[0037] Further detailed description will be made below on the presentinvention on the basis of the examples, but the present invention is notlimited by these examples.

EXAMPLES, COMPARATIVE EXAMPLES

[0038] A piece of C-450 stainless steel plate material was machined intoa square plate of 200 mm on a side and 20 mm in thickness, by using agrinding machine.

[0039] Additionally, slits of 150 μm in the width W and 3 mm in depthwere formed by groove milling with a pitch of 0.9 mm, in a grid pattern,on one end face of the square plate by the machining of grinding (seeFIGS. 2 and 3).

[0040] Furthermore, holes of 0.9 mm in diameter D and 15 mm in depthwere fabricated at the crossover positions of the slits (at every otherpositions) with a pitch of 0.9 mm, from the other end face side of thesquare plate, by means of the ECM processing (see FIGS. 2 and 3).

[0041] The coating films shown in Table 1 were respectively applied ontothe die obtained by the above described method (see FIGS. 2 and 3), andthen extrusion molding of honeycomb structures composed of a cordieritecomposition was performed.

[0042] For this case, the results of the extrusion length required foradjusting the dimensional error in the die and the extrusion length atthe time of extrusion molding of a honeycomb structure are shown inTable 1. TABLE 1 Comparative Example example First coating film 12 Ni—PNi—P (electroless (electroless plating) plating) 28 μm 30 μm Secondcoating film 14 W₂C (CVD) W₂C (CVD) 10 μm 10 μm Surface treatment 35%HCl, — thereafter electroplating >0.1 μm   Third coating film 16 Ni—P —(electroless plating)  2 μm Length required for  100  500 adjustingdimensional dispersion in a die (m) Extrusion length at time 3900 3500of extrusion molding of a honeycomb structure (m)

[0043] (Consideration)

[0044] From the results shown in Table 1, Example is able to adjust thedimensional dispersion of the die in a short time, as compared withComparative Example, and simultaneously to improve the productivity of ahoneycomb structure.

[0045] Additionally, it is confirmed that Example, as compared toComparative Example, eliminated the dimensional error in the die,maintained a stable frictional force of extrusion, and was excellentboth in extrusion moldability and in abrasion resistance.

INDUSTRIAL APPLICABILITY

[0046] The die of the present invention, for extrusion molding of ahoneycomb, can be suitably used for extrusion molding of a ceramichoneycomb.

[0047] Particularly, the die of the present invention, for extrusionmolding of a honeycomb, is possible to eliminate the dimensional errorof the die, and simultaneously is possible to maintain a stablefrictional force of extrusion, is possible to be excellent both inextrusion moldability and in abrasion resistance, and additionally givesan easy adjustment of the die at the time of extrusion molding.

1. A die for extrusion molding of a honeycomb, comprising a structureprovided with a groovy slit formed on a front face thereof by cellblocks and additionally with a puddle inlet, on a back face thereof,communicatively connected with the slit, characterized in that each cellblock has a soft film on a hard film formed on outermost surfaces ofboth the slit and the puddle inlet fabricated in the cell block body. 2.A die for extrusion molding of a honeycomb according to claim 1,characterized in that a Vickers hardness of the soft film is in a rangeof from 500 to
 1500. 3. A die for extrusion molding of a honeycombaccording to claim 1 or 2, characterized in that a thickness of the softfilm is in a range of from 2 to 10 μm.
 4. A die for extrusion molding ofa honeycomb according to any one of claims 1 to 3, characterized in thatthe soft film is an electroless nickel plating film.
 5. A die forextrusion molding of a honeycomb according to any one of claims 1 to 4,characterized in that the hard film is a CVD film comprising, as acomponent, one or more materials selected from a group consisting of W,WC, W₂C, and W₃C.
 6. A die for extrusion molding of a honeycombaccording to any one of claims 1 to 4, characterized in that the hardfilm is a CVD film or a PVD film comprising, as a component, one or morematerials selected from a group consisting of TiC, TiN, and TiCN.
 7. Adie for extrusion molding of a honeycomb according to any one of claims1 to 4, characterized in that the hard film is a composite plating filmhaving a hard powder of SiC, diamond, CBN, or the like dispersed in anickel plating film.